WASHINGTON (CNN) -- Vice President Dick Cheney underwent tests at a hospital Saturday after experiencing shortness of breath, the White House said.

Cheney walked out of George Washington University Hospital on Saturday afternoon, smiled and waved to reporters, but made no comment. Asked how she felt about the incident, his wife, Lynne, said, "Great. Thanks."

Dan Bartlett, the White House communications director, said Cheney has been suffering from a cold recently. (Cheney's health history)

Cheney returned from an annual pheasant hunting trip in South Dakota within the past few days, Matalin said.

Cheney experienced shortness of breath Saturday morning while at his residence and talked to his cardiologist, Matalin said. There was no indication the shortness of breath was related to his heart, but Dr. Jonathan Reiner recommended the hospital tests, given Cheney's history.

"But this was not a scramble," she said. "They went there calmly and in regular order."

Matalin talked to Cheney about two hours before he left for the hospital and told CNN "he sounded fine" and was joking and talking about the recent campaign.

Cheney undergoes regular heart checkups, she said. His most recent EKG, within in the past month or so, was normal.

History of heart problems

Cheney, 63, has had four heart attacks.

His health has been a persistent concern since he was picked as President Bush's running mate in 2000. He had three mild heart attacks and quadruple-bypass surgery before he was 50, and one attack since.

His first came in 1978, when he was 37.

He underwent quadruple bypass surgery in 1988. A coronary stent was inserted in November 2000.

The implant cardioverter defibrillator, a device that monitors and normalizes an irregular heartbeat, was put into his chest in June 2001.Cheney refers to it as his "pacemaker plus."

In May 2004, doctors gave Cheney a clean bill of health after his annual heart checkup. They found that his pacemaker had detected no irregular heartbeat.

President Bush and Cheney won re-election November 2 after a grueling year on the campaign trail.

Cheney, a former defense secretary and congressman, is considered a policy-maker and, outside of the campaign trail, does not often appear in public.

CNN's John King and Elaine Quijano in Washington contributed to this report.